The present invention relates to compound miter saws or other power operated equipment or machinery utilizing a cutter for performing working operations on a workpiece. More particularly, the present invention relates to improvements in an adjustable fence assembly for such power operated equipment, with the fence assembly having a fixed fence and a pair of movable fences for selectively adjusting the gap between the cutter and the movable fences in order to allow sufficient clearance for performing various operations on a workpiece when the equipment is in any of a number of different cutting or working modes.
Saws and other apparatuses designed for cutting or performing other working operations on a workpiece typically require a workpiece-supporting fence in order to support and locate the workpiece in a proper fixed position for performing the working operation. Examples of such equipment include cross-cut compound miter saws which are adapted for allowing the user to selectively move the saw blade into any of a number of positions or modes for square cutting, miter cutting, bevel cutting, or compound miter cutting where a combination miter and bevel are cut. In addition, some operations, such as dado cutting or shaping operations, for example, require the use of saw blades or other cutting or working devices of different shapes or sizes to be substituted for one another in order to perform the desired operation on the workpiece, whether the workpiece is composed of wood, plastic, metal other materials.
In order to accommodate these widely varied working operations, the workpiece-supporting fence is frequently required to be at least partially adjustable in order to selectively vary the gap or space between the saw blade or cutter and the workpiece-supporting fence, thus selectively providing clearance for the saw blade, cutter, or other device performing the working operation on the workpiece. If such adjustability were not available, a relatively large permanent gap would have to be provided between the fixed fence and the saw blade or cutter in order to accommodate the widely varying range of movement, position, or size of the saw blade, cutter, or other working device.
In order to address the above-discussed problems associated with providing clearance for the cutter and support for the workpiece with the incorporation of a movable fence having an adjustable clearance gap, a variety of fence-adjusting arrangements have previously been provided. However, many of such prior fence-adjusting arrangements have suffered various disadvantages, including difficulty in maintaining proper alignment between the stationary fence and the movable fence in wide-gap positions, inconvenience in performing fence adjustment operations, the possibility of inadvertently misplacing a removable fence, lack of adequate support for relatively tall or thick workpieces, or other similar disadvantages. Thus, the need has arisen for an adjustable fence assembly for compound miter saws, or other power equipment requiring fence adjustability, which overcomes these disadvantages, as well as providing improved ease of operation, economy in manufacturing, and other advantages that will become readily apparent to those skilled in the art from the discussion below.
In accordance with the present invention, an improved adjustable workpiece-supporting fence assembly includes a pair of movable fences laterally movably interconnected with a fixed fence which is secured to a base of the device in which it is employed. The pair of movable fences are disposed on opposite sides of a saw blade, a workpiece cutter or other such device for performing a working operation on a workpiece. Each movable fence is independently movable, and is selectively and laterally movably interconnected with the fixed fence on opposite sides of the work-performing blade or cutter. Each is also laterally spaced from the other movable fence located on the opposite side of the blade or cutter. The base or other portion of the device in one preferred form of the invention supports the fixed fence having a fence guide fixedly disposed on opposite sides of the blade or cutter with a laterally-extending slot formed in each of the fence guides. The laterally-extending slots which preferably have spaced opposite internal walls therein are adapted to receive a laterally extending tongue portion on a respective one of the pair of movable fences. The tongue is slidably received within the respective slot for selective adjustable lateral movement of the movable fences toward and away from the blade or cutter.
In the above described preferred embodiment of the present invention, a single fixed clamping arrangement is interconnected with the fixed fence on each side of the saw blade or cutter. Each single fixed clamping arrangement releasably and clampingly urges the tongue on the respective movable fence against the front wall of the laterally-extending slot at any of a number of adjusted positions therein.
In one preferred embodiment of the present invention, the single fixed clamping arrangement includes a threaded clamping member disposed on each outside end (end farthest away from the cutter) of the fixed fence and a locating pad machined into the slot of each fence guide. The locating pads are formed on each side of the saw blade or cutter at the inside end (end closest to the saw blade or cutter) of the fence guide. A corresponding locating surface is formed on the tongue of each movable fence such that the locating surface on the movable fence engages the locating pad on the fence guide when the movable fence is located at its innermost position. The locating pad and locating surface are machined to tight tolerances, thus allowing the utilization of a single threaded clamping member disposed at the outside end of the fixed fence. When the movable fence is moved towards its outermost position, the locating pad disengages from the locating surface at approximately the same time the center of the movable fence is positioned in line with the threaded clamping member thus allowing the utilization of a single threaded clamping member disposed at the outside end of the fence guide.
In an additional preferred embodiment of the present invention, the single fixed clamping arrangement includes a longitudinally extending clamping rod positioned generally parallel to each slot. The clamping rod incorporates a continuous locking lobe or a plurality of locking lobes such that rotation of the clamping rod causes the locking lobe or lobes to clamp the movable fence against the front wall of the slot in the respective fence guide.
In addition, the preferred embodiments of the present invention also include a gap-filling flap pivotably mounted to the inside end of each movable fence. Each gap-filing flap in its lower position is designed to provide additional support for the workpiece at a position immediately adjacent to the saw blade or cutter.
Other advantages and objects of the present invention will become apparent to those skilled in the art from the subsequent detailed description, appended claims and drawings.